The present invention relates to a device for regulating light width of headlights of motor vehicles.
One of such devices is disclosed in the patent document DE-A1 41 22 531. In this device an adjusting device is associated with a headlight and changes the light width of the light beam emitted by the headlight. Moreover, an opto-electronic sensor is provided which detects an illumination situation in front of the motor vehicle. A part of the light emitted by the reflector and reflected from the roadway which is generally is an electromagnetic radiation, is detected by the sensor. The headlight serves here as a transmitter which transmits the electromagnetic radiation in form of visible light. The sensor is connected with an evaluating device in which nominal values for the illumination situation in front of the vehicle are stored. The evaluating device compares the actual illumination situation detected by the sensor with the stored nominal illumination situation and when a deviation occurs, controls the adjusting device for illuminating the deviation. In the evaluating device either illumination intensity values in individual regions of the roadway in front of the motor vehicle are evaluated, or the position the bright-light limit of the light beam emitted by the headlight is determined. In both cases not only a qualitative but also a quantitative evaluation of the illumination situation is required, which needs an expensive evaluation process. For this reason different reflection properties of the roadway represent a substantial unreliable factor which makes the evaluation difficult.